The lighter does not work and I can not use a GPS system. Someone suggested it may be the fuse box, but I don't know which fuse it is because the fuses are not labeled and I don't have an owner's manual. Any ideas?

put your low lights on,see if sigaret lighter lids up.
box under steeringwheel.take out one by one and see whit fuse,
light goes off.is also possible in the cover off the box is indicated whits one it is

The lighter in a Chevy Lumina can get lost easily if you routinely pull it from the socket to plug in electronic devices like GPS systems, cell phone chargers and laptops. If so, you need to replace it.

check fuse for cigarette lighter.

Just go buy a BIC LIGHTER, lol. Just kiddin. If it's the lighter on your CAR, then see if there's a fuse in the fuse box, usually located under the dashboard on the driver's side, and see if you can find a fuse that's burnt out. If that doesn't solve the problem, or you can't find the fuses or don't feel comfortable taking them out and putting them back in, you'll have to take the car to a mechanic who knows how to do that, and also knows how to replace the lighter if that becomes necessary.

It is a 15 amp fuse #12

when you remove the fuze box cover it sould have the fuse placement list on the back side

This sounds like it could be a fuse that has blown. The fuse must be in the main fuse box. The position and function of the fuses is normally marked on the inside of the fuse box cover and also in the owner's handbook. If you don't come right with these, work your way through the fuses looking for a blown one. To ease your search the lighter fuse it should be around 30 amps. A small pair or pliers will help removing the fuses for inspection.

Check your fuse box, it might be that simple. It should be located in the engine compartment (under the hood). When you find the fuse box, there should be a map of each fuse there and what each fuse powers. If one of the fuses is burned out, you should be able to replace it (make sure you use the same rated fuse -- a 20Amp for a 20Amp, or a 5Amp for a 5Amp -- usually they are color coded) and that should solve the problem. Japanese cars USUALLY have all of the fuses under the hood, but there is a chance that there might be a fuse box (or second fuse box) in the glove compartment, or under the dashboard.
If the fuse is not the problem, there might be a short circuit between the fuse box and the broken components. Bad wiring is much less likely, and much harder to fix, so if it is worth it for you to get it fixed, I recommend visiting a professional mechanic. If you don't want to invest that much money to repairing the issue, but need the Cig lighter to power a cell phone charger or GPS, you can run a bypass wire from the fuse box straight to the cig lighter. This will give you back your lighter, but will not solve the problem, which could indicate something more important, so it would be good to have a professional mechanic check it out when you have the time and money.

you will find it on the fuse box cover

Look under the hood on the driver's side near the windshield, there should be another fuse box there and the fuse is in that one. Good luck!